121 lines
3.5 KiB
C
121 lines
3.5 KiB
C
/*
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* QEMU Crypto block IV generator - essiv
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*
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* Copyright (c) 2015-2016 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "qemu/bswap.h"
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#include "crypto/ivgen-essiv.h"
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typedef struct QCryptoIVGenESSIV QCryptoIVGenESSIV;
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struct QCryptoIVGenESSIV {
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QCryptoCipher *cipher;
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};
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static int qcrypto_ivgen_essiv_init(QCryptoIVGen *ivgen,
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const uint8_t *key, size_t nkey,
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Error **errp)
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{
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uint8_t *salt;
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size_t nhash;
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size_t nsalt;
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QCryptoIVGenESSIV *essiv = g_new0(QCryptoIVGenESSIV, 1);
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/* Not necessarily the same as nkey */
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nsalt = qcrypto_cipher_get_key_len(ivgen->cipher);
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nhash = qcrypto_hash_digest_len(ivgen->hash);
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/* Salt must be larger of hash size or key size */
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salt = g_new0(uint8_t, MAX(nhash, nsalt));
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if (qcrypto_hash_bytes(ivgen->hash, (const gchar *)key, nkey,
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&salt, &nhash,
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errp) < 0) {
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g_free(essiv);
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return -1;
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}
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/* Now potentially truncate salt to match cipher key len */
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essiv->cipher = qcrypto_cipher_new(ivgen->cipher,
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QCRYPTO_CIPHER_MODE_ECB,
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salt, MIN(nhash, nsalt),
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errp);
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if (!essiv->cipher) {
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g_free(essiv);
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g_free(salt);
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return -1;
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}
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g_free(salt);
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ivgen->private = essiv;
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return 0;
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}
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static int qcrypto_ivgen_essiv_calculate(QCryptoIVGen *ivgen,
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uint64_t sector,
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uint8_t *iv, size_t niv,
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Error **errp)
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{
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QCryptoIVGenESSIV *essiv = ivgen->private;
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size_t ndata = qcrypto_cipher_get_block_len(ivgen->cipher);
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uint8_t *data = g_new(uint8_t, ndata);
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sector = cpu_to_le64(sector);
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memcpy(data, (uint8_t *)§or, ndata);
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if (sizeof(sector) < ndata) {
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memset(data + sizeof(sector), 0, ndata - sizeof(sector));
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}
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if (qcrypto_cipher_encrypt(essiv->cipher,
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data,
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data,
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ndata,
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errp) < 0) {
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g_free(data);
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return -1;
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}
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if (ndata > niv) {
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ndata = niv;
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}
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memcpy(iv, data, ndata);
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if (ndata < niv) {
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memset(iv + ndata, 0, niv - ndata);
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}
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g_free(data);
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return 0;
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}
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static void qcrypto_ivgen_essiv_cleanup(QCryptoIVGen *ivgen)
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{
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QCryptoIVGenESSIV *essiv = ivgen->private;
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qcrypto_cipher_free(essiv->cipher);
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g_free(essiv);
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}
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struct QCryptoIVGenDriver qcrypto_ivgen_essiv = {
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.init = qcrypto_ivgen_essiv_init,
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.calculate = qcrypto_ivgen_essiv_calculate,
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.cleanup = qcrypto_ivgen_essiv_cleanup,
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};
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